Paper container construction



p 1966 R. L. MORSE ETAL PAPER CONTAINER CONSTRUCTION 2 Sheets-Sheet 1 F IG. 2.

Filed Feb. 5, 1964 FIG. 1.

FIG. 5.

INVENTORS Rama/rd L. Horse Pala/ [hr/er BY W 2 ATTORNEY Sept. 13, 1966 R. L. MORSE ETAL PAPER CONTAINER CONSTRUCTION Filed Feb. 5, 1964 2 Sheets-Sheet 2 7 QB!) l/lliiiiiiiii FIG. IO.

PLASTIC) 22 INVENTORS I \w Emma/rd L. Norse PAPER FIG. 8. BY dz fi ATTORNEY United States Patent 3,272,418 PAPER CONTAINER CONSTRUCTION Raymond L. Morse and Paul H. Carter, Baltimore, Md., assignors to Maryland Cup Corporation, Owings Mills, Md., a corporation of Maryland Filed Feb. 5, 1964, Ser. No. 342,645 4 Claims. (Cl. 2291.5)

This invention relates to paper containers and it is more particularly concerned with the closed end construction of such containers.

An object of the invention is the provision of a construction for the closed end of a paper container to render it leakproof against liquid contents.

Another object of the invention is the provision of such a construction which can be applied to provide either a flat bottom or a recessed bottom.

A further object is the provision of means for manufacturing a flat bottom or recessed bottom container by rolling a fiat sheet of paper on a frusto-conical mandrel and finally sealing the bottom in a hot mold.

A still further object of the invention is the provision of a preformed blank sheet of paper that can be rolled into the shape of a frusto-conical container having either a flat bottom or a recessed bottom and then heat sealing it to a permanently retained shape.

These objects and still further objects and advantages of the invention will be apparent from the following description and the drawing which accompanies it.

In the drawing:

FIG. 1 is an elevational view of a cup formed in accordance with this invention.

FIG. 2 is a longitudinal sectional view along the line 2-2 of FIG. 1.

FIG. 3 is a top plan view of the embodiment.

FIG. 4 is a plan sectional view along the line 44 of FIG. 1 with parts broken away.

FIG. 5 is a bottom plan view of the same embodiment partly broken away.

FIG. 6 is a plan view of a sheet of paper which has been coated with a thermoplastic material and cut and shaped to provide a blank for forming the embodiment.

FIG. 7 is a bottom plan view of the blank shown in FIG. 6 at an intermediate stage in the formation of the end structure showing the relationship of the tongues relative to each other.

FIG. 8 is a sectional view along the line 8-8 of FIG. 6.

FIG. 9 is a view similar to FIG. 6 of a modified form of blank for producing a cup having a recessed bottom.

FIG. 10 is a longitudinal sectional view of a cup formed by means of the blank shown in FIG. 9.

FIG. 11 is a schematic view showing the manner of heat sealing the tongues which form the bottom of the cup in a mold and which comprises one of the steps of the process of the invention.

In the manufacture of paper containers it is important that the cost of production be low because such containers are usually provided for use only once and then discarded. In order to keep the cost of production low, consideration must be given to the cost of the materials used as well as the cost of the method of production. To this end it is obvious that minimum costs will be achieved by using inexpensive paper sheets formed into blanks having a minimum of cut-out parts and a forming procedure that results in a minimum of overlapping of the parts of the blank and a minimum of operations to secure the blank after it is formed into the desired shape.

The present invention is particularly useful in making so-called hot cups, that is, cups capable of holding hot liquids like hot coffee, hot tea, hot chocolate, etc., with- "ice out taste contamination. Cups of this type are conventionally provided with an inner coating of a plastic material that seals the pores of the paper and protects it against the hot liquid without taste contamination. However, at temperatures considerably above the temperatures of such hot liquids the coating material becomes plastic and the present invention takes advantage of this fact by forming a paper blank with a coating of such thermoplastic material thereon and then using this paper coating as the means for heat sealing portions of the blank together to form the finished cup.

The blank sheet for forming the cup is shown in FIG. 6 and it is in the general shape of an arcuate strip having a relatively larger outer arcuate edge 11 and a relatively small inner arcuate edge 12. The blank is formed so that marginal portions adjacent the opposite side edges 13 and 14 overlap each other in the final cup structure and are heat sealed together.

A marginal area adjacent the inner acruate edge 12 is provided with radial slits 15 forming a series of consecutive tongues 16, 17, 18, 19, 20 and 21. Ideally, the best results are obtained when the tongues are of equal size and exactly six in number, a shown. The blank is then rolled into a conical shape on a form or mandrel (not shown) and the tongues are arranged in overlapping relation as shown in FIGS. 3, 4, 5,. and 7. The tongues positioned in this way are heated and pressed together to seal the overlapping surfaces with the thermoplastic coating 22. This may be effected by any conventional means such as a hot mold as shown in FIG. 11 comprising a female part 23 and a heated male part 24.

The final arrangement of the tongues are such that each tongue is turned under and lapped to overlie its adjacent tongue on one side and to underlie its adjacent tongue on the other side in a continuous circle as clearly shown in FIG. 7. With six tongues, each one will have a corresponding diametrically opposite tongue such as the tongues 16 and 19, 17 and 20 and 18 and 21 and each pair can be disposed with their outer edges lying in a common vertical plane to form the bottom section. When the length of these tongues are each equal to onehalf the diameter of the bottom of the cup to be formed there results a flat bottom structure at right angles to the longitudinal axis of the cup as shown in FIG. 6. However, when the tongues are of a length greater than onehalf the diameter of the bottom of the cup there is formed in this relationship the generally conical of pyrimidal bottom structure recessed from the lower edge of the cup as shown in FIG. 10. In both forms of cup the center of the cup bottom is common to a point between the outer ends of each tongue. In other words, the outer edge of the tongues have a common intersection point at the center of the cup bottom.

The blank for forming the cup in FIG. 10 is illustrated in FIG. 9 and is substantially the same as that of FIG. 6 except that the tongues 25, 26, 27, 28, 29 and 30 are longer, that is, each greater than one-half the diameter of the bottom of the cup. The greater the length, the deeper the recess. Accordingly by controlling the length of the tongues the amount of the recess can be provided as desired.

The advantage of a recessed cup is to provide a more stable support on a horizontal surface when the cup is filled with a liquid. It also facilitates nesting of the cups and removing them one at a time from a nested relation.

Having thus described our invention, we claim:

1. A paper blank for forming a cup comprising an arcuate strip of paper coated with a thermoplastic material, said strip having a relatively large outer arc edge and a relatively small inner arc edge, said strip having spaced radial slits extending inwardly from the inner arc edge forming tongues, the length of said tongues being at least one-half the diameter of the bottom of the cup to be formed.

2. A blank as defined by claim 1 in which the length of the tongues are exactly one-half the diameter of the bottom of the cup to be formed.

3. A blank as defined by claim 1 in which the length of the tongues are each greater than one-half of the diameter of the bottom of the cup to be formed.

4. The method of manufacturing a paper cup comprising forming a blank from a thermoplastic coated sheet of paper in the shape of an arcuate strip having a relatively large outer arcuate edge and a relatively small inner arcuate edge, slitting a marginal portion of the blank adjacent the inner arcuate edge to form a series of tongues having each a length equal to at least the diameter of the cup at the bottom thereof, shaping the blank into a conical form with the outer arcuate edge at the top and the inner arcuate edge at the bottom and disposing the tongues in lapping relation in a circle with each tongue overlying an adjacent tongue on one side and underlying an adjacent tongue in the other side, then subjecting the lapping surfaces of the blank to heat and pressure to cause the thermoplastic coating to seal the lapping surfaces together.

References Cited by the Examiner UNITED STATES PATENTS 397,475 2/1889 Tiifany. 1,030,637 6/1912 Beadle. 1,472,211 10/ 1923 Gallistel. 1,904,365 4/1933 Geist 2292l 2,014,477 9/1935 Lee 229-21 2,431,537 11/ 1947 Bogoslowsky.

GEORGE O. RALSTON, Primary Examiner. 

1. A PAPER BLANK FOR FORMING A CUP COMPRISING AN ARCUATE STRIP OF PAPER COATED WITH A THERMOPLASTIC MATERIAL, SAID STRIP HAVING A RELATIVELY LARGE OUTER ARC EDGE AND A RELATIVELY SMALL INNER ARC EDGE, SAID STRIP HAVING SPACED RADIAL SLITS EXTENDING INWARDLY FROM THE INNER ARC EDGE FORMING TONGUES, THE LENGTH OF SAID TONGUES BEING AT LEAST ONE-HALF THE DIAMETER OF THE BOTTOM OF THE CUP TO BE FORMED. 